I've found that you have to spread out your industrial areas so that the goods can get to the different places on your map. The more your city expands the harder it is to get from one area of industry to your entire city. Also, make sure your trucks have a clear as day shot at the businesses.

I had this exact problem when my city hit 80k, it just takes traffic fixing and spreading your industry out. Also, having those industry train stations in the middle of your city might help. Good luck!